I think Carl was afraid during the confrontation with the other kid, but didn't want to admit it to the others. You could see his hand shaking holding the pistol, so there is a good chance he fired the gun by accident. From what Hershel saw, and Carl's refusal to admit he fired by accident, makes him look like a cold-blooded killer. It may be the path he is headed on, but I don't think he is there yet.
4/1/13 at 2:48pm